1. Field of the Invention
The present invention relates to a method of thin film growth and more particularly to a method of thin film epitaxial growth using atomic layer deposition.
2. Description of the Prior Art
Atomic layer deposition (ALD) is a technique that allows growth of thin films. For a conventional ALD application, each deposition precursor is alternately pulsed into a carrier gas stream which continuously flows into an ALD chamber and an inert purge gas is introduced into the ALD chamber between each deposition precursor pulse to evacuate the ALD chamber. The conventional ALD process is not suitable for epitaxial growth and for thin films having preferred orientation because the partial pressure of the deposition precursor in the chamber is not stable and a substrate within the chamber is not in thermal equilibrium while reacting with the deposition precursor.
Furthermore, pulsing molecular precursors to uniformly fill high aspect ratio features on the substrate in a short time is difficult because there is no sufficient time for deposition precursors to diffuse to the deep surface on the substrate effectively. Although a conventional ALD method is proposed to resolve the aforementioned issues by extending the time for introducing deposition precursors into the chamber, the resulting deposition precursor consumption is high because most of deposition precursors have not reacted with the substrate before being removed by a vacuum pumping system.